1. Field of the Invention
This invention relates to the method for removing dissolved oxygen in water by deaeration, as well as to the deaerating apparatus with which the method is practised.
2. Description of the Prior Art
Plugging of water supply pipings and contamination of the supplied water, which are caused by rusting of the pipings or water tanks, are commonplace problems in ordinary office buildings, apartment houses, etc. Among various factors promoting the rust formation in the water supply system, dissolved oxygen concentration in water appears to be the most important. For example, lowering of the dissolved oxygen concentration to half results in nearly doubled time required for rust formation of the same degree. In other words, there is an approximately proportional relation between the dissolved oxygen concentration and growth rate of the rust. Consequently, formation or growth of rust can be substantially inhibited by removing the dissolved oxygen.
Practically, however, prevention or inhibition of rust formation by removing the dissolved oxygen is not adopted in water supply systems for ordinary office buildings, apartment houses, etc. Instead, troublesome cleaning operations for removing rust formed in the water supply system are conducted periodically or at need.
According to prior operation, the dissolved oxygen is removed by means of vacuum deaerator equipped with ejector, or deaerator utilizing vacuum pump in conjunction with membrane.
But these conventional apparatuses such as the vacuum deaerator equipped with ejector and deaerator utilizing vacuum pump in conjunction with membrane are costly and not easily applicable to ordinary houses and apartment houses, because they not only require relatively sophisticated controlling technique but consume large quantity of electric power for the operation.